PNG with indexed colour mode presents incorrect colours in VapourSynth

[mrhso]

(FFMS2 ver 5.0)
RGB:
Indexed:
Using AviSynth+ 3.7.5 on Windows x86-64, both obtained the correct colour.

StackHorizontal(FFMS2("rgb.png"), FFMS2("indexed.png"))

Using VapourSynth R72 on Windows x86-64, RGB is correct but indexed is incorrect.

import vapoursynth as vs
core = vs.core

clip = core.std.StackHorizontal([core.ffms2.Source('rgb.png'), core.ffms2.Source('indexed.png')])
clip.set_output()